I followed this article to generate WIX installers for ESP.Portal, ESB BAM Service, ESB Exception Service and ESB UDDI service using Visual Studio 2013. It worked well.
The ESB Portal Management Portal sample that comes with ESB Toolkit 2.3( BizTalk 2013R2) has some minor changes from the previous versions; compilation uses the .Net Framework 4.5 and some of the self generated classes have changed. The installer projects for the web services are no longer supported in Visual Studio 2013. I used WIX to create some new installers that can be used to install the services on servers that do not have Visual Studio installed.